Bioaccumulation of Heavy Metals in Artisanal Miners and Associated Health Risk Assessment in Michika Local Government Area, Adamawa State, Nigeria

Artisanal and small-scale mining (ASM) is a widespread economic activity in Michika Local Government Area (LGA), Adamawa State, Nigeria. Despite its economic value, ASM poses significant environmental and public health challenges due to heavy metal contamination. This study assessed the levels of bioaccumulated heavy metals specifically lead (Pb), cobalt (Co), chromium (Cr), arsenic (As), iron (Fe), manganese (Mn), zinc (Zn), and copper (Cu) in soil, water, and blood samples from mining locations. The analysis was carried out using atomic absorption spectrophotometry (AAS) Model: AA320N. High concentrations of Pb (2.89 ppm), Co (0.16 ppm), and Cr (0.34 ppm) in soil were found to exceed World Health Organization (WHO) limits, while heavy metals like Fe,Co and Pb in water where higher in some locations like Garta, Sina mala.. Blood analysis of artisanal miners revealed significant bioaccumulation, particularly for Pb (mean: 25.94 µg/L), As (12.54 µg/L), and Mn (14.36 µg/L), with several values exceeding WHO safety thresholds. Bioaccumulation factors (BAF) and correlation analysis confirmed water as a major exposure pathway. Health risk assessments indicated high hazard quotients (HQ > 1) and unacceptable cancer risks (CR > 1.0×10-4) in mining communities such as Garta, Garta Sama and Sina Mala. These findings reveal the urgent need for environmental remediation, strict regulation of ASM practices, and health monitoring programs for affected populations in Michika LGA. Keywords: ASM, Heavy metal, Bioaccumulation, WHO, Hazard quotient and Cancer risk